The 18-55mm for now, until you learn the camera should suffice.
Might be slow indoors - consider investing in an external flash and a nice sturdy tripod. Should help with indoor situations.
For better lens around $300... I might suggest you take a look at older lenses from Pentax, Sigma or Tamron. You could find some good deals for some still great lenses.
As for the ranges... well, depends on what you plan for the future.
For portraits, if you are comfortable with manual lenses and you want a good lens for a great price you might want to invest in a nice prime lens - something like this:
Rokinon 85mm F 1 4 F1 4 Lens FOR Pentax K20D K10D K200D 084438002065 | eBay
For even better lenses... $500 and up will be easily spent...
For now, 18-55, is good enough
.